Party-line selective signaling system.



G. E. SGRIBNER.

PARTY LINE SELECTIVE SIGNALING SYSTEM. APPLIUATIOK FILED A1 11. 18. 1908.

1,023,482, Patented Apr.,16, 1912.

E C Zddm$66kfi (La kg) [j ag g jflc z'n r following is a UNITED sracrns PATENT OFFICE.

CHARLES E. SCRIBNER, 01:.JEBICHQ, VERMONT, ASSIGNOB TO WESTERN ELECTRIC COMPANY, OF CHICAGO, ILLIFOIS, 'A CORPORQTION OF ILLINOIS.

rAs-rYLmnnsnmcrrvssmimtnm srs'rnia.

To all whom it may concern: 7 I ,Be it known that I, CHARLES E. Soamnaa, citizen of the United States, residing at Jericho, in the county of Chittenden and State of Vermont, have invented a certain new and useful Improvement in Party-Line Selective Signaling Systems, of which the full, clear, concise, and exact description.

My invention relates to party line selective signaling systems, and is an improvement upon that party line telephone signaling system which is illustrated, described and claimed in Patent No. 555,725 to Angus S. Hibbard, dated.,-Mareh 3rd, 1896. This,

' Hibbard system hasbeen largely employed,

and under the most favorable conditions has been found satisfactory. In the ractical operation of the system some modifications were introduced, among which I would mention that in each of the branches to ground at the different subscribers substations there was included with the bell a resistance of about six thousand ohms, this resistance, added to the resistance of the bells emplo ad, which was about a thousand ohms, ma 'ng seven thousand ohms resistance or thereabout in each ground branch at each of the substations of a party lin'e, Notwithstanding all the improvements or chan es that were-thus introduced into the llibbard system, difliculties were encountered in connection with the oieration, not only of the individual bells, but also in the operation of the supervisory relay and the line relay, due to line leakage, necessarily inherent inthe system, and to earth voltages. Installations of that prior system in which the telephone lines are in proximity to power circuits, resulting in earth voltages, and also'where the telephone lines themselves var in length, capacity and resistance, and w ere the various substations upoira given line are at widely ditlerent distances apart, havebeen found quite unsatisfactory and even inoperative on account of the cross ringing of the bells, such cross ringing or false signaling resulting from some unfavorable condition at another station of the same line.

Earth potentials, as is well understood, may be thirty or forty volts where telephone lines are installed near electric railwaysand other utilities which employ electric current sent over wires and to ground. Variations in the voltage and frequencies of Specification of petters ratent. I Application filed 4 5m 18, race. Serial no. 427,955.

' load increase t unfavorably as desirable to decrease to speed of the generator and ariations in already enumerated, and have resulted so to render the Hibbard system, if not whollyinoperative, at least ex ceedi'ngly unsatisfactory.' Itwill further be understood that in the 'Hibbard system the margin between the high resistance reuired to make the leakage. moderate and Ifate'nted Apr. 16, '19 12.

7 the signaling e difiicultie's which I have t e requirement thatthere shallbg. enou h current to operate the bells is not wi e.

Even when t e greatest care is taken there will be some normal flow of battery current which in the'interestsof economy it is consistent with practical operation. The

bells or rin ersatthe difierent stations are biased. Pu eating current of the *plus -sign 'will accordingly operate a'bell biased in a given direction, while the same bell will not e rung when traversed by pulsations of the opposite sign. y

My invention is designed to avoid all the the lowest amount I objections to the Hibbard system that have been enumerated.

Speaking generally, my, invention consists in providing condensers in connection with the circuit of each party line substation, each condenser being in parallel with or shunted by a very high resistance, the connection to groun at each substation being made through a biased bell. Each bell is preferably mechanically attuned to cause the .bell in each case to res end with maximum effect when traversed y current of the lowest practical voltage and frequency.

In carrying out my invention, I have found that a pulsating current of a peculiar wave form is very desirable if not essential to the commercial success of my system. The ordinary pole changer produces circuit waves which are abrupt, increasing almost instantly to a maximum and then receding to zero in the same abrupt way. The ordinary generator produces a wave is only less abrupt, the u per corners, so to speak, of the pu sations Eeingrounded off. Theoretically, the form which I would prefer is one in which a single impulse increases to its maximum abruptly and then falls away gradually to zero.

The attuning of the bells is an important feature of my invention. The bells may be constructed to respond best when the generator is constructed and operated to send form which tit pulsations at the rate of say a thousand pulsations per minute, the voltage impressed upon the line being at the same time only of the amount. which is adapted to cause the bell); to operate in a satisfactory manner; that is to say, I attune or weight the bells so as to be in harmony with the amount of rolta e and number of impulses produced when t ie generator is operated at its practical minmnun of speed such speed, for example, as will cause a thousand impulses a minute upon the line, or some speed near the practical minimum. In case the speed is increased, the number 'of impulses will be increased in like ratio, and the bells being attuned or weighted, the increase in the fre ueney of the ilnnllses will make their et'ect. upon the bells less etl'ective. That is to say, if the number of impulses shall be increased above the rate of a thousand :1 minute, this being a normal rate to which the bells have been attuned, the increase in frequency will make their ell'ect upon the bells less, so, that the bells will be lrss liable to cross ringhw. \ccordingly, when on increase in voltage due to increase in speed of the generator, the tendency to cross ringing would be amplilicd on account of the increase in the discharge from the condensers, this increased tendency due to increase in voltage will he oll'set 0r luade harmless on account of the increase in the number of pulsations when the bells are attuned to the lower rate of vibration in ac- (ordance with my invention. lly weighting or attuning the bells so that they will perate with he desired clliciency when the speed of the generator is moderate. I am enahlcd to maintain such desired ellicieneg. in the operation of the hells when the speed of the generator is considerably increased, hecau c the negative etl'ect caused by the increase of pulsations is oll'set' or counterbalanced by the positiviell'ect resulting from the increase in the voltage of the adsations due to the increase of the speed of operation. I am thus enabled to cau e the hell of a station whigh it is desired to i 'ual to respond, while at the saine lilnc, hel s of other stations are prrrcnlcd l'roni cross iiogiug.

.\ly invention will he more readily under stood by reference to the accoiu anrving drawing, wherein Figure l illustrates a Four-party line circuit tttlttlt'tflWl with ccutral ollice apparatus in accordance with my invention; Fig. 5! illustrates graphically the form of pul-alion product-l hy the m'dinary polechu ngcr; l 'ig. it illustrates the form of pul- .'-ttlt lt produced by the ordinary generator; Fig. 4 illustrates the form of pulsation which i c nsider in lhcory lnost practical and ell cicnt in my system; Fig. 5 Illustratcs the l'orln ol' pulsation which I have used in actual practice and which has provcn eminently satisfactory; and Fig. it illustrates the conformation of the pole pieces of a generator adapted to produce tinform of pulsation illustrated in Fig. 5.

Like parts are designated by similar characters of reference throughout the several views.

In Big. 1 I have illustrated only so much of a party line telephone circuit as is necessary to make clear the nature of my invention. It will be seen that the telephone line circuitconsists of two limhs, l. 2, extending from the central ollice out through four substations ll U I). At the central ollicc is prorided the usual cut-otl' relay 3, and the line relay 4. The line is shown connected with springjack switches Fl, (3 and 7, aswould be required in a multiple system, though the multiple arrangement is not a feature of my invention. The limb l is branched to ground through substations l) and (l. Limb 2 is branched to ground through substations ll and A. The ringer S'at. substation A is biased to respond to negative impulses. 'l'he ringer ll at sub tathan B is biased to res mud to positive impulses. At station C t to ringer 10 will respond to negattre nu ullses, while the ringer at substation i) will respond to posh tivc impulses.

to the ground branches of the dill'ercnt snhstations place condensers. each condenser being in shunt of a very high non-inductive resistance. The condensers 1;! may each have a capacity of say two nlirmfarads, and the resistance l3 about the same may he of say sixty thousand ohms. i preferably lttilh't! the ringers 8, J, to and it each of about twenty-live hundred ohlns resistance. They will have also necessarily rather high innit-dance. The transmitter H. the receiver 15 and the telephone switchhook lt'i are of the usual form and may be connected in any well-known lnauncr.

Referring to the central olllci' apparatu the line relay -'l will he of any usual constructi n and arranged and adapted to opz-ralc the call signal ii. 'l'hc cord circuil iio-lu'h-s the three part plug IS and the i switch lccys it), ill, .I and .22, corn-sponding .rcspcclively with substati ns ll l The op rator'slistening-in hey B l will he of usual construction. I have not shown the operatofs telephone set. 'lhe super- \isory relay .'.l is connected with the t'tlltl circuit in the ordinary manner to control I the clearing-out signal.

l l haurepresentml the ringing generator l in the usual diagrammatic form. It is adapted as shown to impress upon the line citlu-r alternating current or positive pulsations or negative pulsations, according to l the connection made. 'l'he. key 35, which is l adapted to nndm connection with the brush IOU Ill)

I 26 which controlsthe alternating current, is used when it may be desired to signal the substation'upon a non-party line such a single station is ordinarily provided .with

the usual polarized ringer. From brush 27 positive pulsations will be derived, and from rush 28 ne ative pulsations. The attuning of the bells s brought about by makin the bell striker of the desired weight wi ie spect to the striker rod. The inertia of the' striker wilLt-hus' be made suflicient so that pulsations of the moderate or normalgrate wilL be practically inunison with the nor- 1 mal movement or vibrations of the striker of the ringer under operation. That is-to' say, the ringers are constructed so that they is important in connection with; the charging and discharging of the condensers. Let

, us assume that key 22 is depressed when the plug 18 is inserted in the springjack of the line. The pulsating current acting throu h the condensers will cause the signal to e given by the ringer IL The condenser 12 .111 the same circuit witl'n'ringer 11 will be pulsations of the form he discharge, however, It will be. apparenttliat charged abruptly b shown in Fig. 5. T will be gradual.

when current made up of positive impulses is sent through ringer 11 that the same kind of positive pulsations will be sent .throu h ringer 10, but rin er 10 is biased opposite y to ringer 11, and, therefore, will not respond. There is, however, current produced of the negative polarity through ringer 10 when its corresponding condenser is discharged. The object of theresistances 13 is to give the condensers in each case a chance to discharge in the local circuit through its resistance instead of through the corresponding ringer, as ringer 10.

By making the form of the circuit pulsations substantially such as described in connection with Figs. 4 and 5, the discharge of the condensers is made grad'uahas distinguished from the abrupt manner in which it was charged, and therefore the current produced bythe discharge of a condenser which is necessarily of the opposite sign to that of the pulsations of the current by which .it was charged, will be better taken care of in the local -circuit containing the resistance and by the impedance of the bell, and thus a ringer which might be falsely operated if pulsations were of the form shown in Fig. 2

"nor Fig. 3 will not be operated if the pulsations are of the form shown in Fig. 4 or Fig.

'5. In the llibbard system there was necessarily a waste of current goin on due to leakage through the ringer, of t e station of a given limb of a circult, which it was not desired to operate.

greatl In the prior systems to which reference has been made, not only have the ringers been caused to operate poorly by leakage andearth potentials, but also the signaling apparatus at the central oflice,.part1cularly the line relays and the supervisory relays have been caused to act erroneously, the line signal being disclosed orv withdrawn when .it should not, and the clearing-outer supervisory signal being falsely operated by abnormal currehts caused to traverse the supervisory relay. By the use of my invention, all these various difiiculties in the operation of party line circuits have been overwhere the ofthe several 'lines lines between party stations vary in length -In ig. 6 pole. pieces of a generator'adapted. to roduce the form .of pulsatory current t for It will be-tea y seen that in a generator' of. 'the'construction indicated, the armature winding will be cutting the largest number of lines of forceat the beginnin approximatel ofits rotary movement adfigure being driven in a clockwise direction) and therefore at that time carrying the peak of the wave. As the winding continues'its hiovementbetween the pole pieces, the flux decreasing and the number of the lines of force out in any given movement decreasthe wave will gradually-s10 e to zero and produce thereby the form 0 wave desired. It should be understood that while I have illustrated this meansfor obtaining the de-- sired wave, since it forms no part of my present invention, any means whereby the desired wave form may be obtained may be substituted.

While I have illustrated the telephonecirswitches supposed to be upon difl'erent sections of a multiple switchboard, it is evident that my invention might be applied to systems in which other forms of circuit and other switchboards are employed. While in the cord circuit is shown the centralized battery 29 and the repeating coils 30, it is evident that'my invention may be applied to ordinary magneto systems.

Having thus described my invention, what I claim and desire to secure by Letters Patent is 7 1. A circuitextending from the central oflice of a telephone exchange to two liffen ent substations, each substation being provided with a ground branch, the respective ground branches each including a condenser having high non-inductive resistance about the same, and a ringer of high self-induction come, even where earthpotentials exist and I have shown a detail of the I and particularly of the difierent portions of ada ted for use'in m system as herein set V jacent thejpo e-pieces, (the armature in the ing owing to the recision of the pole faces,

cuit as a metallic circuit and shown three 

